A snowboard is essentially a single wide ski provided with one or more platforms for supporting both feet of a skier. These snowboards can be of various configurations, as exemplified by U.S. Pat. Nos. 3,900,204 and 4,403,785. Typically, a snowboard includes fore and aft fixed boot bindings, which allow the skier to place one of his feet at an angle with respect to the longitudinal axis of the board, as opposed to the axial boot alignment of conventional skis. The snowboarder's stance is dictated by the need to maintain balance. Typically, both the ankles and knees flex during snowboarding to allow weight shifting to adjust for changing conditions, such as when making turns or when attempting to slow down. Consequently, conventional ski bindings, which rigidly maintain a boot parallel to the ski longitudinal axis are not considered acceptable for use on snowboards.
In U.S. Pat. No. 4,652,007, a releasable binding system is disclosed for use on a snowboard. The system uses releasable toe and heel binding clips secured to the snowboard with a mounting plate placed on the toe and heel clips along a longitudinal axis of the snowboard. These clips are adapted from conventional ski bindings. Each mounting plate has a pair of laterally extending portions, extending parallel to the rider's feet and means for securing a boot to the plate. The rearwardly located mounting plate is placed normal to the snowboard and the forwardly located mounting plate is secured at a predetermined angle relative to the longitudinal axis of the snowboard. The toe and heel clips release the boot and mounting plate in a manner similar to conventional ski bindings. However, since the toe and heel clips are placed along the longitudinal axis of the snowboard, forces acting other than normal to the snowboard and the rider may not cause release to occur. Also, these are total release bindings, with no provision for absorbing forces and for automatic resetting of the mounting plate once the upsetting force has subsided. Similar to conventional ski bindings, once release occurs, the rider is released from the snowboard.
In U.S. Pat. No. 4,079,962, a releasable ski binding is disclosed using a sole plate and a flexible cable housed in the sole plate, extending from opposite ends thereof. The ends of the cable are secured to the ski, with one end of the cable fixed securely to the ski by a plate and the other end secured to a turning element supported on a shaft held on the ski. The front part of the sole plate has a complementary profile which cooperates with the edge of a cable engaging element, to hold the plate on the ski in a longitudinal direction parallel to the longitudinal axis of the ski. The binding uses a pair of cable engaging elements spaced apart from each other, the elements being movable closer to each other to lengthen the cable to provide a partial release of the sole plate from the ski. The elements are biased to force them away from each other with the breakaway force being sufficient to overcome the biasing and thus allow lengthening of the cable. However, such a binding system again is dependent on the application of a predetermined force acting in a particular direction to cause lifting of the sole plate and release from the ski. Also, the sole plate breaks away from the ski.
While usable for conventional skis, such a binding system is not readily adaptable to snowboard bindings which must accommodate changes in the user's weight distribution which varies over a range of angles relative to the snowboard and absorb the dynamic forces encountered during snowboarding.